Linear compressor

ABSTRACT

The present invention refers to a linear compressor based on resonant oscillating mechanism, which comprises an oscillating arrangement essentially formed by at least one linear motor ( 2 ) defined by a movable portion ( 22 ) and a fixed portion ( 21 ), at least a resonance spring ( 3 ), at least one piston ( 4 ) and at least one balancing body ( 5 ), wherein the movable portion ( 22 ) of the linear motor ( 2 ) is cooperatively associated with the piston ( 4 ), defining a piston-motor assembly. The piston-motor assembly is operatively associated to the end ( 31 ) of the resonant spring ( 3 ) and at least one balancing body ( 5 ) is functionally associated with the end ( 32 ) of the resonant spring ( 3 ). This construction allows the attenuation of the vibration that the resonant oscillating mechanism applies to the compressor housing through the cancellation of the forces generated by the motor and the forces generated by the compression of gas in the cylinder.

FIELD OF THE INVENTION

The present invention refers to a linear compressor based on resonantoscillating mechanism, in particular based on a resonant spring-masssystem, for maintaining the oscillating movement of its components. Thelinear compressor in question provides a resonant oscillatingarrangement responsible for attenuation of vibration imposed on theirouter housing.

BACKGROUND OF THE INVENTION

Briefly, linear compressors consist of a piston which is responsible foradmission and compression of the working fluid, coupled to a linearmotor. The linear motor is responsible for imposing the linearoscillatory motion to the piston, which is responsible for thecompression of the fluid. Compressors that make use of a linear motor ontheir drive have the advantage of occupying a substantially small volumecompared to the compressors driven by a conventional rotary motor.

The use of a compact compressor is regarded as preferred and as thevolume occupied by a compressor which is driven by a linear motor issignificantly lower than the volume occupied by a compressor driven by arotary engine, various solutions arose to seek the increase of theperformance of the compressors driven by linear motors, the so-calledlinear compressors.

Based on the resolution of this drawback, linear compressors began toemerge provided with means focused on minimizing the force that thelinear motor needs to perform in each cycle. One of these solutionsreside in the use of a physical principle to conserve energy of thesystem, using the alternative movement of the linear motor and extendingit in such a way that the effort made by the linear motor is aided bythe inertia of the system. The resonance phenomenon is used.

The resonance is the tendency (or facility) that a body has to oscillatewith large amplitudes at certain frequencies, called natural frequencyor resonant frequency.

Once a force is imposed at a frequency near the natural frequency of abody, there is a gradual accumulation of mechanical energy, resulting inthe increase of the amplitude of oscillation of the system.

Thus, solutions appeared which comprise a linear motor mounted undersupports comprising springs, which have the function of accumulating theenergy delivered by the engine. In addition to the accumulation ofenergy, these springs have the function of transmitting the movement ofthe motor to the piston. These springs are commonly called as resonantsprings.

The use the resonant of springs helps linear motor to work and reducesthe effort required to move the set, resulting in lower electricityconsumption of the linear motor that drives the system, due to the factthat most part of the energy required to move the piston is alreadystored in the spring resonant.

A first example of linear compressor provided with resonant springs isdescribed in the document US 2006/005700, which discloses a linearcompressor provided with an assembly of resonant springs, associatedwith the piston, which is in turn associated with the movable core of alinear motor. Said assembly of resonant springs consists of two pairs ofsprings, each pair disposed in a face of a plate associated with thepiston. Thus, when performing the linear movement of the piston in onedirection, the pair of springs arranged in the respective face of theplate acts on the assembly and moves it in the opposite direction whenthey reach a certain level of openness, reducing the effort that themotor needs to operate in alternating manner. This embodiment has,however, the inconvenience of using a large amount of springs, whichcomplicates the mounting of the assembly. Furthermore, this embodimentprevents the minimization of the compressor assembly, preventing itsapplication in small devices.

A second example of a linear compressor provided with resonator springsis described in document PI 0601645-6, which discloses a minimizedcompressor, comprising a single resonant spring associating a linearmotor and a piston, and give it a reciprocating motion performed by thelinear motor. This embodiment, while enabling a more compact arrangementof the linear compressor, has the disadvantage of not providing theexistence of any deviation in the position between the piston and thelinear motor, since each component is disposed at one end of theresonant spring. Furthermore, such a constructive arrangement, to use asingle spring arranged along the entire length of the compressor,without any guiding element, results in undesirable efforts of thepiston and of the motor, which may preclude their correct functioning.

A third example of the linear compressors provided with resonant springsis illustrated schematically in FIG. 1 with a resonant linear compressorCL, according to the state of the art, comprising a piston P mountedwithin a cylinder CM and associated with a first end of a resonantspring MR, which has its second end associated with a movable portion(moving magnet) PM of a linear motor. The resonant spring MR has aneutral portion PN associated to the housing C of the compressor by afastening means MF. Therefore, it should be noted that the linearcompressor CL of the state of the art employs the piston P being mountedon a first end PE of the housing C, and the motor mounted on a secondend SE of the housing C, that is, each component in one of the ends ofthe compressor. These components are intermediated by the resonantspring MR, however, this motor and piston arrangement is not favorabledue to the resulting vibration in the compressor housing, since theforces generated by the engine and the forces generated by thecompression of gas in the cylinder are in phase, that is, in the samedirection, and therefore they are added, resulting in a greater force onthe housing.

Thus, it is noted that the current state of the art lacks a resonantcompressor comprising a constructive simplified arrangement which can beminimized and, moreover, provided with means to reduce vibration of thehousing.

OBJECTIVES OF THE INVENTION

It is one of the objectives of the present invention to provide a linearcompressor based on resonant oscillating mechanism capable ofattenuating the vibration that said resonant oscillating mechanismapplies to its carcass. In this sense, then it is another objective ofthe present invention to provide a linear compressor whose resonantoscillation arrangement is able to promote the cancellation (evenpartially) of the forces generated by the motor and of the forcesgenerated by compression of the gas in the cylinder.

It is another objective of the present invention to provide a linearcompressor based on resonant oscillating mechanism whose resonantoscillating arrangement reduces the amplitude of the resultant forces(movement) imposed on its housing.

SUMMARY OF THE INVENTION

The objectives of the present invention are fully achieved by the linearcompressor shown herein, which comprises an oscillating arrangementessentially comprising at least one linear motor (defined by a movableportion and a fixed portion), at least one resonant spring and at leastone piston. The oscillating arrangement further comprises at least onebalancing body.

According to the concepts of the present invention, the movable portionof the linear motor is cooperatively associated with the piston defininga piston-drive assembly.

In this sense, the piston-motor is functionally associated to one of theends of the resonant spring, while at least one balancing body isfunctionally associated with the opposite end of the resonant spring.

Thus, the mentioned balancing body is capable of exerting an oscillatorymovement, which can be synchronized to the resonant oscillatory motionof the motor piston assembly, or, synchronously opposite to the resonantoscillatory motion of the piston-motor assembly.

BRIEF DESCRIPTION OF FIGURES

The present invention will be described in detail based on the figureslisted below.

FIG. 1 illustrates a schematic view of the assembly of the resonantlinear compressor belonging to the current state of the art.

FIG. 2 illustrates a schematic view of the assembly of the resonantlinear compressor that is object of the present invention.

DETAILED DESCRIPTION OF FIGURES

According to the main concept of the present invention, there is shown alinear compressor based on resonant oscillating mechanism (driven by alinear motor and which makes use of a resonant spring to assist itsoperation through the accumulation of energy resulting in an increasedoscillation amplitude), where the resonant arrangement itself is capableof minimizing the unbalanced forces from the gas compression in thecylinder and the oscillating operation of the motor. With this, thevibration that the resonant arrangement applies to the housing of thelinear compressor is attenuated.

FIG. 2 shows a schematic (cross-sectional) view of the preferredconstruction of the linear compressor 1, which is designed in accordancewith the concepts and objectives of the present invention.

Thus, the preferred construction of a linear compressor 1 comprising anoscillating arrangement essentially comprising a linear motor 2, aresonant spring 3, a piston 4, and a balancing body 5. Notably, thelinear compressor 1 also comprises a cylinder 6 and other elementsconventionally existing in compressors (for example, as a head assembly7 and connections 8 for suction and discharge of the working fluid).Preferably, the linear compressor 1 is also integrated by a housing 9which has the function of accommodating all components that form thementioned linear compressor 1.

The linear motor 2 comprises, in general, a fixed portion 21 (stator orback iron) and a movable portion 22 (cursor/magnet). The linear motor 2is, therefore, a conventional linear motor.

According to the present invention, the fixed portion 21 of the linearmotor 2 is fixed to the casing 9 of the linear compressor, or anyintermediate element (not shown) also fixed to the frame 9 of the linearcompressor 1. Since the movable portion 22 of the linear motor 2 iscooperatively associated with the piston 4 defining a piston-motorassembly.

The resonant spring 3 includes a physically resilient body, that is,capable of suffering physical “deformation” when subjected to anexternal force and capable of returning to its original “form” when freeof external force.

Preferably, the resonant spring 3 is a substantially helical tubularmetal body defining two distal ends 31 and 32. The resonant spring 3further comprises a neutral point 33 (where vibrations or deformationsare much smaller than the ends 31 and 32) arranged in the middle of itslength. Said neutral point 33 allows the resonant spring 3 to beattached to the casing 9 of the linear compressor 1, or any intermediateelement (not shown) also attached to the housing 9 of the linearcompressor 1.

The piston 4 is one conventionally piston used in linear compressors,that is, it comprises a piston defined by an essentially cylindricalbody with an open end and one closed end (working end).

The balancing body 5, as induced by its nomenclature, consists of a bodywith a specific mass. Preferably, the balancing body 5 has a masssimilar to the mass of the piston-motor assembly.

The cylinder 6, the head 7 and the connections 8 for suction anddischarge of working fluid comprise conventional components alreadybelonging to the current state of the art, therefore, already known tothose skilled versed in the art.

The housing 9 which provides attachment means 91 to the neutral point 33of the resonant spring 3 (or to any intermediate element disposedbetween said resonant spring 3 and the housing 9) also comprises aconventional housing already belonging to the current state of the art.

According to the main concepts of the present invention, the oscillatingarrangement is especially detached from other oscillatory arrangementsof the same type and belonging to the current state of the art due tothe fact that the piston-motor assembly (defined by the cooperativeassociation between the movable portion 22 of the linear motor 2 and thepiston 4) is functionally associated with the end 31 of the resonantspring 3, while the balancing body 5 is functionally associated with theend 32 of the resonant spring 3.

In this sense, the movement of the movable portion 22 of the linearmotor 2 is integral and directly transmitted to the piston, therebymoving the piston-motor assembly, and consequently, the end 31 of theresonant spring 3. This movement is transmitted to the end 32 of theresonant spring 3 and, consequently, to the balancing body 5.

Thus, each component of the oscillating arrangement described herein hasits particular function, namely:

The piston-motor assembly (defined by the cooperative associationbetween the movable portion 22 of the linear motor 2 and the piston 4)serves to impose movement on the resonant spring 3 and function ofcompressing, effectively, the working fluid.

The resonant spring 3 has a function to amplify the oscillatingmovement, by accumulating mechanical energy.

The balancing body 5 has the task of balancing the system, so that theforces generated by piston-motor assembly (at the time of compression ofthe working fluid) are annulled (by the forces generated by the movementof the balancing body itself).

Thus, the main objective of the present invention (attenuate thevibration that the resonant oscillating mechanism requires thecompressor housing by canceling (even partially) the forces generated bythe motor and the forces generated by compression of the gas in thecylinder) is successfully achieved.

It is also worth mentioning that, as the piston-motor assembly, thebalancing body 5 performs an axial, linear and oscillating movementinside the housing 9 of the linear compressor 1. This movement can besynchronized or synchronously opposite to the resonant oscillatorymovement of said piston-motor assembly.

Having described an example of a preferred embodiment of the presentinvention, it should be understood that the scope of the same includesother possible physical variations, which are limited solely by thewording of the claims, with the inclusion of the possible equivalentmeans.

1. Linear compressor, comprising a oscillating arrangement fundamentallyformed by at least one linear motor (2) defined by a movable portion(22) and a fixed portion (21), at least one resonant spring (3) and atleast one piston (4); the compressor being especially CHARACTERIZED inthat: the oscillating arrangement comprises at least one balancing body(5); the movable portion (22) of the linear motor (2) is cooperativelyassociated with the piston (4) defining a piston-motor assembly; thepiston-motor assembly is functionally associated with the end (31) ofthe resonant spring (3); and at least one balancing body (5) isfunctionally associated with the end (32) of the resonant spring (3). 2.Linear compressor according to claim 1, CHARACTERIZED in that thebalancing body (5) is capable of having an oscillatory movement. 3.Linear compressor according to claim 2, CHARACTERIZED in that thebalancing body (5) is capable of performing a resonant oscillatingmovement synchronized with resonant oscillatory movement of thepiston-motor assembly.
 4. Linear compressor according to claim 2,CHARACTERIZED in that the balancing body (5) is capable of performing aresonant oscillating movement synchronously opposite to the resonantoscillatory movement of the piston-motor assembly.